Gas turbines are commonly used to drive generators for power generation and/or to drive process equipment such as compressors or pumps. To drive the process equipment and/or the generators, gas turbines may receive and compress motive air in a compressor, combust the compressed motive air with fuel in a combustor to produce a combusted motive gas, and expand the combusted motive gas through a power turbine. Generally, it is necessary to provide one or more cooling flows to keep certain components of the gas turbine (e.g., metal components of the combustor and/or power turbine) within acceptable temperature ranges.
Typically, air may be utilized to provide the cooling, and the cooling air is derived from the compressor at one or more stages thereof and ported to the combustor and/or power turbine either internal or external to the gas turbine. In the event that it is desired to operate a combustor and power turbine that is not coupled directly to and integrated with the compressor, such as would be the case in a compressed air energy storage (CAES) system, the cooling flows directed to the combustor and/or power turbine may be provided by other cooling sources and process components, such as, for example, heat exchangers. However, the use of these cooling sources and process components may lead to losses in efficiency.
What is needed, therefore, is an efficient system and method for cooling components of a gas turbine not integrally coupled with the compressor thereof.